Formerly, there is a technique of reducing the occupied area of a semiconductor device by sticking multi-stage chips each having semiconductor elements and an integrated circuit formed thereon to a substrate. An insulation layer is provided on each sticking plane of chips stuck, and a plurality of electrodes connected by sticking chips together are provided in corresponding positions of respective insulation layers. Such chips are polished to become flat in sticking surfaces, and then stuck.
In a process of polishing sticking surfaces of respective chips, however, a sticking surface of an insulation layer and a sticking surface of an electrode are not flush with each other in some cases. In such a case, a faulty joint occurs in a joint portion between chips, resulting in a lowered yield.